I would be upset to if I where you.
There is something wrong with this as the others have said.
I wouldn't marry this person .
i agree with vance.....he probably wanted to see if your daughter would.....well you know. watching porn in the same room as your fiance's young daughter is unacceptable! did your daughter say why she didn't sign off of msn and leave the area? i know she shouldn't have to but i know if my moms husband did that....oh god i wouldn't be able to leave the room fast enough!
you may want to sit down with both of them. individually and then together.
Let me ask you, was it hard core porn or porn that you find on Cinemax?
Either one is not right to be watching in the same room as a 20 year old. You are right in thinking that you watch porn for arousal. My thinking is that he turned it on, wanted to get aroused and wanted to see if your daughter would do anything with him. Now this is just my thought on the subject I can't say for a fact because I am not him. But what do men do when watching porn...they masterbate.